code: def __init__(self, lr):
      super().__init__()
      self.lr = lr
  
file_path: nnabla/python/test/solver/test_sgd.py
imports: import pytest
  import nnabla.solvers
  import numpy
  from solver_test_utils import solver_tester, RefSolver
  from nbla_test_utils import list_context
label_desc: Use image node_id 1 to create a new RefSgd object from inherited base classes: RefSolver with example: obj = RefSgd(lr)